If i had to guess, i bet it's the other machines nearby. I'm sure we've all felt the static from a crt screen when it's turned off. Being in a closed room of turned on crt's would probably create a significant field of potentials around the room. I can't imagine the earth's magnetic field is so erratic as to change noticeably from room to room. I'd think any variation of that order would disrupt the functioning of compasses, and the phenomena couldn't just be localized to your one room on earth, compasses would be somewhat unreliable all over the globe then.

But who knows, maybe a solar flair hit you between rooms and changed the environment enough to disrupt the tv, but then i'd bet it'd effect all the machines. Eh, who knows. Weird thing that electromagnetism